Effectiveness of Maternal Vitamin D Supplementation in Preventing Respiratory Tract Infections in Children.

Vitamin D exhibits a hormone-like action in our body and the deficiency or insufficiency of vitamin D is known to be related to the occurrence or prognosis of various diseases. In the Korean Journal of Family Medicine, papers on the relationship between vitamin D levels and colon polyps [1], autoimmune thyroid disease [2], lung function [3], dry eyes [4], cardiovascular disease risk [5], and quality of life [6] were published. Among these effects, vitamin D is known to play an important role in bone growth and immune function. Although it is known that the administration of vitamin D reduces respiratory infections, there has been an interest in whether vitamin D administration during pregnancy reduces respiratory tract infections (RTIs) in newborns.

In the present issue, Sulaiman et al. [7] investigated the effect of maternal vitamin D supplementation in preventing RTIs in children. This systematic review selected three randomized controlled trials with a total of 3,224 participants (mother–infant pairs). It was found that maternal vitamin D supplements had no effects on RTIs among children (n=1,486 offspring; risk ratio, 0.95; 95% confidence interval, 0.82–1.11; random effects; I2 statistics, 0%).

A systematic review on a topic similar to this study was published twice, but the conclusions of the two reviews were different. The systematic review by Christensen et al. [8] showed results supporting a preventive role of vitamin D during pregnancy on the risk of RTIs in offspring, whereas the systematic review by Tareke et al. [9] showed that there is no significant evidence to promote vitamin D supplementation. However, based on these results, it can be said that maternal vitamin D supplementation had no effect on RTIs in children.

Moreover, these results do not mean that pregnant women have no need for vitamin D supplementation. A study found that 4,000 IU of vitamin D daily had the greatest benefits in preventing preterm labor/births and infections [10], and most institutions recommend vitamin D supplementation during pregnancy. Therefore, vitamin D supplementation should be continued. However, supplementation is not necessary to reduce RTIs in children since its effect is insignificant.